U.S. patent number 5,986,582 [Application Number 09/103,521] was granted by the patent office on 1999-11-16 for helicopter rotor/engine warning system.
This patent grant is currently assigned to Safe Flight Instrument Corporation. Invention is credited to Leonard M. Greene, Randall A. Greene.
United States Patent |
5,986,582 |
Greene , et al. |
November 16, 1999 |
Helicopter rotor/engine warning system
Abstract
A two-stage alarm for a rotary wing aircraft, such as a
helicopter which operates on a collective control arm. A moveable
mass or weight is operatively connected to the collective control
arm. The moveable weight may be of a reciprocating type or a rotor
driven mass which is mounted eccentrically for rotation about an
axs which is spaced from the center of gravity of the weight. In
the latter case, a D.C. motor spins the weight rapidly about the
axis at a first speed to produce a shaking action to the collective
control arm as a warning of an approaching danger. The weight is
moved more rapidly to produce a much more noticeable action at a
second frequency, or at an increased amplitude as a warning of a
more imminent or serious condition which requires immediate
action.
Inventors: |
Greene; Leonard M. (White
Plains, NY), Greene; Randall A. (Boulder, CO) |
Assignee: |
Safe Flight Instrument
Corporation (White Plains, NY)
|
Family
ID: |
26315900 |
Appl.
No.: |
09/103,521 |
Filed: |
June 24, 1998 |
Current U.S.
Class: |
340/965; 340/945;
340/964; 340/971; 340/966; 340/946; 340/963; 340/969; 340/973;
340/968; 340/970 |
Current CPC
Class: |
G05D
1/0055 (20130101); B64C 27/56 (20130101); B64C
27/006 (20130101); B64C 13/10 (20130101) |
Current International
Class: |
G05D
1/00 (20060101); G08B 023/00 () |
Field of
Search: |
;340/946,945,963,964,965,966,967,968,969,970,971,973 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lee; Benjamin C.
Attorney, Agent or Firm: Dougherty & Troxell
Claims
What is claimed is:
1. A tactile warning system for a helicopter having a rotor with a
plurality rotor blades and a collective pitch adjusting mechanism
for collectively adjusting pitches of the rotor blades, the warning
system comprising:
a) a movable collective control arm connected to the collective
pitch adjusting mechanism whereby movement of the collective
control arm collectively adjusts the pitches of the rotor
blades;
b) a storage device storing first and second pre-selected values
for a plurality of flight characteristics of the helicopter;
c) sensing devices for sensing values of actual flight
characteristics of the helicopter corresponding to the flight
characteristics in the storage device;
d) a comparator receiving inputs from the storage device and the
sensing devices to compare the values of the actual flight
characteristics to both the first and second pre-selected values
for the plurality of flight characteristics; and,
e) a shaker mechanism for shaking the collective control arm, the
operation of the shaker mechanism controlled by an output from the
comparator such that the shaker provides a first level of tactile
sensory perception when any of the values of the actual flight
characteristics exceed a corresponding first pre-selected value,
and a second level of tactile sensory perception when any of the
values of the actual flight characteristics exceed a corresponding
second pre-selected value.
2. The tactile warning system according to claim 1 wherein said
shaker mechanism includes an eccentrically mounted weight and an
electric motor for rotating said eccentrically mounted weight about
an axis whereby the inertial rotation of the unbalanced weight
produces vibration of the collective control arm.
3. The tactile warning system according to claim 2 in which said
electric motor is a D.C. motor and wherein said D.C. motor is
operated at a first voltage to provide said first level of sensory
perception and at a second voltage to provide said second level of
sensory perception.
4. The tactile warning system according to claim 2 in which said
electric motor is operated at a first speed to provide said first
level of sensory perception and at a second speed to provide said
second level of sensory perception.
5. The tactile warning system according to claim 2 in which a
frequency of vibration of the collective control arm in the second
level of sensory perception is greater than a frequency of
vibration for the first level of sensory perception.
6. The tactile warning system according to claim 2 in which said
shaker mechanism is mounted on said collective control arm.
7. The tactile warning system according to claim 1 wherein the
shaker mechanism includes a weight that is moved in a reciprocating
manner.
8. The tactile warning system of claim 1 wherein the first
pre-selected values are indicative of an approaching dangerous
flight condition, and the second pre-selected values are indicative
of an immediate dangerous flight condition.
9. The tactile warning system of claim 1 wherein the storage device
stores first and second pre-selected values of engine torque and
wherein the sensing device senses actual values of engine
torque.
10. The tactile warning system of claim 1 wherein the storage
device stores first and second pre-selected values of exhaust gas
temperature and wherein the sensing device senses actual values of
exhaust gas temperature.
11. The tactile warning system of claim 1 wherein the storage
device stores first and second pre-determined values of rotor speed
and wherein the sensing device senses actual values of rotor
speed.
12. The tactile warning system of claim 1 wherein the storage
device stores first and second pre-determined values of output
shaft speed and wherein the sensing device senses actual values of
output shaft speed.
13. The tactile warning system of claim 1 wherein the storage
device stores first and second pre-determined values of turbine
inlet temperature and wherein the sensing device senses actual
values of turbine inlet temperature.
14. The tactile warning system of claim 1 wherein the storage
device stores first and second pre-determined values of engine
torque and exhaust gas temperature and wherein the sensing device
senses actual values of engine torque and exhaust gas
temperature.
15. The tactile warning system of claim 1 wherein the storage
device stores first and second pre-determined values of output
shaft speed, rotor speed, engine torque, exhaust gas temperature
and turbine inlet temperature, and wherein the sensing device
senses actual values of output shaft speed, rotor speed, engine
torque, exhaust gas temperature and turbine inlet temperature.
Description
FIELD OF THE INVENTION
This invention relates to an aircraft control system and more
particularly to a tactile warning system for alerting a pilot of
dangerous and/or near dangerous conditions.
BACKGROUND FOR THE INVENTION
Control column shakers or stick shakers for fixed-wing aircraft are
well known for unmistakably relaying advance warning of an
impending stall. Such shakers have been adapted for use on high
performance and other aircraft. They are typically mounted on the
aircraft's control column. These units electrically provide a high
amplitude, low frequency buffet signal to a pilot. Such signals
cannot be confused with other warnings and provide a pilot with a
reliable stall warning. Control column shakers of various designs
are presently manufactured and sold by Safe Flight Instrument
Corporation of White Plains, N.Y., the assignee on the present
invention.
The uses of control column shakers in rotary wing aircraft have
also been disclosed, as in U.S. Pat. No. 4,115,755 to Cotton. As
disclosed therein, an alarm, such as a shaking of the collective
pitch control lever of a helicopter, is used as an indication that
the actual acceleration exceeds the permissible acceleration. As
disclosed by the Cotton patent, the structural envelope of the
aircraft, as defined by weight, air speed, rotor rpm, air density
and collective stick position, is used as an indication of
permissible loading of a helicopter rotor. Cotton also teaches the
use of a gross measure of the aircraft weight, density of the air,
air speed, the collective pitch and rotor speed of the aircraft as
indices of a table look-up to determine the maximum permissible
aircraft acceleration under such flight conditions which is then
compared against the actual aircraft acceleration to determine when
the aircraft is maneuvered close to a loading which exceeds a
structural envelope. cl SUMMARY OF THE INVENTION
It is presently believed that there is a significant demand for an
improved collective control shaker in accordance with the present
invention. It is believed that there is a significant demand for a
two-stage tactile warning system which alerts a pilot that he/she
is approaching a dangerous condition and then warns the pilot when
immediate corrective action should be taken. With this approach,
the pilot can fly the aircraft close to its critical limitations
and at the same time take corrective action when it becomes
necessary.
The collective control shaker in accordance with the present
invention provides a first sensory warning when the aircraft is
close to a relatively critical stage with respect to any one of a
number of flight conditions. For example, as the aircraft
approaches a dangerous condition, the shaker vibrates the
collective control at a first frequency or amplitude to alert the
pilot to either push the collective in a downward direction, or to
at least be prepared to do so. Then if any one of a number of
flight characteristics becomes more critical, the shaker produces a
more violent shaking to provide a vigorous sensory signal to
indicate the need for immediate action.
The tactile warning system in accordance with the present invention
enables a pilot to fly a helicopter safely at maximum loading
within its structural envelope. The system provides an alert
signal, such as a vibration of the collective control at a first
frequency or amplitude when any one of several operating parameters
reaches a first preselected level. The system then provides a more
noticeable signal, such as a violent shaking, which overrides the
first signal when any one of several parameters becomes critical.
The operating parameters may include engine torque, exhaust gas
temperature, rotor speed, turbine output shaft speed, turbine inlet
temperature, etc.
In addition, the tactile warning system in accordance with the
present invention is durable, reliable and can be manufactured,
installed and serviced at a competitive cost.
In essence, the present invention contemplates a two-stage alarm
for a rotary wing aircraft, such as a helicopter. The alarm
operates on a collective control arm of the type used in the
control of helicopters. A moveable mass or weight is operatively
connected to the collective control arm as, for example, by being
mounted thereon or bolted thereto. The moveable weight may be of a
reciprocating type or a rotary driven mass which is mounted
eccentrically, i.e. for rotation about an axis which is spaced from
the center of gravity of the weight. In the latter case, means such
as a D.C. motor spins the weight rapidly about the axis at a first
speed to produce a shaking action to the collective control arm as
a warning of an approaching danger. Means are also provided for
moving the weight more rapidly, as for example by a higher voltage,
to produce a much more noticeable action at a second frequency, or
at an increased amplitude as a warning of a more imminent or
serious condition which requires immediate action.
A tactile warning system in accordance with a preferred embodiment
of the invention includes a collective control arm and a shaker
mechanism operatively connected to the collective control arm. The
shaker mechanism may be mounted on, bolted or otherwise fixed to
the collective control arm. The system also includes means for
sensing a first pre-selected flight condition which is indicative
of an approaching danger and a second pre-selected flight condition
which is indicative of a more imminent danger and means for
producing first and second signals in response to the sensed
conditions. The shaker mechanism includes means for producing a
first level of sensory perception in response to the first of the
signals and a second level of sensory perception which overrides
the first level of sensory perception in response to the second
signal. In this way, a pilot is warned that he/she is operating a
helicopter near a dangerous condition and then given a second
warning when the condition becomes critical. The invention will now
be described in connection with the following drawings wherein like
reference numerals have been used to indicate like parts.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a helicopter collective control arm in
accordance with one embodiment of the invention wherein a
reciprocating shaker is shown in cross-section:
FIG. 2 is a top view of a helicopter collective control arm in
accordance with a preferred embodiment of the invention wherein a
rotary shaker is shown in cross section: and,
FIG. 3 is a schematic diagram which illustrates the sensing of the
flight characteristics in the operation of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
As shown in FIG. 1, a helicopter collective control arm 2 which is
of conventional design and as used in the control of the collective
pitch of a helicopter includes a reciprocating shaker mechanism 4
mounted on the arm 2, such as on the top thereof The shaker
mechanism may be bolted to the top of the arm 2, held thereon by
threaded fasteners (not shown), or attached thereto in any other
conventional manner.
The reciprocating mechanism 4 comprises an alternating solenoid
which includes a solenoid coil 6, magnetic circuit 8 and
shuttlecock or plunger 10. Strikers 12 and 14 are disposed one on
each end of the plunger 10 and are adapted to strike end plates 16
and 18 as the plunger moves back and forth within the solenoid coil
6. The plunger 10 which is shown in its energized position is
biased in the opposite direction by a coil spring 20 so that the
striker 12 will strike the end stop 16 when the solenoid is
de-energized.
A second embodiment of the invention incorporates a conventional
stick shaker mechanism of a type manufactured by Safe Flight
Instrument Corporation of White Plains, N.Y. and identified as a
side-mounted shaker. As shown in FIG. 2, the shaker mechanism 40
includes a generally cylindrical housing having a forward portion
42 and rear portion 43. As illustrated, the forward portion 42 has
a larger diameter than the rear portion 43. A D.C. motor 44 is
disposed in the rear portion 43 and is generally coaxial therewith.
The rear portion 43 also includes a connector 46 for connecting the
motor 44 to a source of power or energy (not shown). A shaft 50 and
an eccentric weight 52 which is mounted on the shaft 50 are
disposed in the forward portion 42 of the housing. The eccentric
weight 52 is keyed to the shaft 50 and rotated by the motor 44
through a gear train assembly 54. The gear train assembly 54 is
separated from the eccentric weight and shaft by partition 56 which
includes conventional bushing assemblies to rotatably support one
end of shaft 50 and the gear train shaft. The forward portion 41 of
the housing 42 is then closed by an end cap 58.
The reciprocating mechanism 4 and the shaker mechanism 40 are
controlled in response to a plurality of operating parameters, such
as output shaft speed, rotor speed, engine torque, exhaust gas
temperature and turbine inlet temperature. As illustrated in FIG.
3, known sensors monitor these parameters and compare them to a
first reference value, REF 1, and a second reference value, REF 2,
via comparators 60a-60j. Should any sensed parameter exceed the
first reference value, REF 1, the comparator will transmnit a first
signal which will cause the mechanism to reciprocate or rotate to
cause the collective control arm to vibrate at a first frequency or
amplitude to warn the pilot of the approach of a potentially
dangerous operating condition. Should any sensed parameter exceed
the second reference value, REF 2, a second signal will cause the
mechanisms to vibrate the collective control arm at a second, more
violent frequency or amplitude to warn the pilot to take immediate
corrective action to avoid impending danger.
Although the invention has been described using two reference
values, quite obviously more than two reference values may be
utilized without exceeding the scope of the invention. It is also
within the scope of this invention to utilize different operating
parameters to provide the activation signal for the disclosed
vibrating mechanisms.
While the invention has been described in connection with its
preferred embodiments, it should be recognized and understood that
changes and modifications may be made therein without departing
from the scope of the appended claims.
* * * * *